The European Partnership on Metrology project BiometCAP (Protocol for SI-traceable validation of methods for biomethane conformity assessment) has developed a comprehensive performance assessment protocol tailored to benchmark and characterise analytical systems such as gas analysers. The outcomes, including practical tests, will contribute to the development of standards. This article highlights some of the findings obtained so far in the BiometCAP project, showing the applicability of this protocol to assess the performance of analysis techniques used for quantifying terpenes, siloxanes and halogenated volatile organic compounds in biomethane.